Pythonize automate `run_unit_tests.sh`

[aaaaalbert]

0bb6e2e added a wrapper script to freshly check out SeattleTestbed repos, building them, and running the unit tests.

To be really useful (across platforms etc.), we should port this script to Python.

Let's also think about collecting the results in a meaningful way, and how we could automate these tests to the point that we run them continuously on a set of dedicated machines/VMs and get notifications if new commits cause tests to fail

[vladimir-v-diaz]

Although the Seattle Testbed might not be buildable with Travis CI, nor support all of Seattle's target platforms, we can use the Github API to build a CI server.

It will be convenient to trigger builds of the SeattleTestbed repositories on multiple platforms (our VMs), and run the unit tests when a commit or pull request is made.